Glass fiber reinforced products (FRP) include glass fiber marine craft, showers and bathtubs, building and automotive panels, swimming pools, satellite dishes, and the like.
Conventional FRP construction methods include the construction of a mold, the application of a releasing agent such as a wax to the mold, the application of a gel coat to the waxed mold, and the application of a glass fiber reinforced laminate to the gel coat. The unsaturated polyester resin contained in the gel coat and the ensuing laminating resin which binds the glass fiber reinforcement is a styrene or styrene/methyl methacrylate, free radical initiated, liquid thermosetting resin which upon catalysis with an organic peroxide such as methyl ethyl ketone peroxide, gels and cures to a solid thermosetting state.
Accordingly, when the FRP is removed from the mold, the glass fiber reinforced laminate is covered by the decorative layer of gel coat.
The a gel coat may be pigmented or unpigmented, but most FRP laminates have a pigmented gel coat for esthetic purposes.
Unfortunately, prolonged exposure to ultraviolet radiation affects the gel coat in several detrimental ways. For example, a gel coat exposed to sunlight and other elements will lose its gloss in a relatively short period of time. This loss of gloss is known in the FRP industry as chalking.
Moreover, white and off-white gel coats turn yellow upon exposure to weathering; pastel colors darken or fade.
Medium colored gel coats (blacks, dark blues, greens, reds, etc.) also fade or darken upon exposure.
Gel coat requires an organic peroxide as a catalyst for gel and cure; its cure is dependent upon catalyst concentration, ambient temperature and humidity. Thus, chemical reaction sensitivity is another undesirable effect of weathering on gel coat.
The known shortcomings of gel coat have spurred inventors to find ways to protect it from the elements. One popular protection technique is to make the FRP in the conventional manner and to apply a protective coating over the gel coat when the FRP has been removed from the mold (demolded).
That technique is unsatisfactory, however, because the post-applied protective layer separates from the gel coat because a good bond is not achieved.
Specific prior art methods are shown in the following U.S. Pat. Nos.: 4,123,582; 4,209,486; 4,239,808; 4,244,993; 4,248,816; 4,331,735; 4,356,230; 4,367,192; 4,414,173 and 4,528,227.
There is a clear need for an improved process for making FRP laminates; the improved process would result in a protected gel coat, but the prior art contains no teachings or suggestions as to how the art could be advanced.